A. Technical Field
The present invention relates to rate sensors. More particularly, the invention relates to systems, devices, and methods of providing shock robustness for MEMS rate of rotation sensors, such as gyroscopes.
B. Background of the Invention
MEMS gyroscopes are sensors that when continuously excited by driving electronics to perform a primary oscillation can sense a rotation rate about one or more axes by detecting deflections of mechanical structures that result from forces caused by the Coriolis effect.
A common problem of MEMS gyroscopes is that it may be exposed to different types of external mechanical disturbances, such as shock, vibrations, and other undesirable environmental mechanical noise that can negatively impact the sensor's excitation and rate measurement. In general, a shock is a combination of forces and momentum with arbitrary orientation within a three-dimensional system of coordinates. In other words, mechanical disturbances may comprise six components—three translational and three rotational components.
External mechanical disturbances have numerous side effects, including the creation of spurious output signals that falsify the sensor's reading, e.g., when a shock event induces a deflection similar to a to-be-detected deflection created by a Coriolis force. The two superimposing signals may corrupt the rate measurement. Second, when shock events are great enough to cause the proof masses within the gyroscope to contact stopper structures that are attached to the substrate and designed to limit the displaceability of the masses, they lose some of their kinetic energy, and the sensor's primary oscillation will have to be restarted during which time the entire device remains inoperable.
Shock robustness of gyroscopes, especially in automotive and similar applications, is a highly desirable feature that would allow gyroscopes to remain functional and deliver accurate electric output signals even in scenarios when the device is subject to certain levels of mechanical disturbance.
What is needed are devices, systems, and methods for system designers to overcome the above-described limitations.